﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;
using System.Web;

namespace V5_Common {
    public class ImageHelper {
        /// <summary>
        /// 动态输出图片
        /// </summary>
        /// <param name="imagePath"></param>
        /// <param name="width"></param>
        /// <param name="height"></param>
        /// <param name="waterPath"></param>
        /// <param name="waterFont"></param>
        /// <param name="mode"></param>
        public static void ImageResponse(string imagePath, int width, int height, string waterPath, string waterFont, string mode) {
            try {
                System.Drawing.Image originalImage = System.Drawing.Image.FromFile(imagePath);
                int towidth = width;
                int toheight = height;
                int x = 0;
                int y = 0;
                int ow = originalImage.Width;
                int oh = originalImage.Height;
                switch (mode) {
                    case "HW"://指定高宽缩放（可能变形）                
                        break;
                    case "W"://指定宽，高按比例                    
                        toheight = originalImage.Height * width / originalImage.Width;
                        break;
                    case "H"://指定高，宽按比例
                        towidth = originalImage.Width * height / originalImage.Height;
                        break;
                    case "Cut"://指定高宽裁减（不变形）                
                        if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight) {
                            oh = originalImage.Height;
                            ow = originalImage.Height * towidth / toheight;
                            y = 0;
                            x = (originalImage.Width - ow) / 2;
                        }
                        else {
                            ow = originalImage.Width;
                            oh = originalImage.Width * height / towidth;
                            x = 0;
                            y = (originalImage.Height - oh) / 2;
                        }
                        break;
                    default:
                        break;
                }
                //新建一个bmp图片
                System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
                //新建一个画板
                Graphics g = System.Drawing.Graphics.FromImage(bitmap);
                //设置高质量插值法
                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
                //设置高质量,低速度呈现平滑程度
                g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                //清空画布并以透明背景色填充
                g.Clear(Color.Transparent);
                //在指定位置并且按指定大小绘制原图片的指定部分
                g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
                    new Rectangle(x, y, ow, oh),
                    GraphicsUnit.Pixel);
                //输出到浏览器
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                HttpContext.Current.Response.ClearContent();//Response.ClearContent();
                HttpContext.Current.Response.ContentType = "image/Jpeg";
                HttpContext.Current.Response.BinaryWrite(ms.ToArray());
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
                HttpContext.Current.Response.End();

            }
            catch (Exception) {
                HttpContext.Current.Response.End();
            }
        }
    }
}
